الفهرس 
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Abstract
The present study aimed to assess the effectiveness of several cleaning techniques for decontaminating zirconia and vita enamic materials, while also examining their impact on colour, surface roughness, and shear bond strength to resin cement.
A total of one hundred and forty (140) samples were produced, each measuring 10 mm in diameter and 3 mm in height. The samples were categorised according on the type of ceramic material utilised, resulting in two groups: Zirconia samples (n = 70) and Vita enamic samples (n = 70). Each group was further divided into seven subgroups, with each subgroup consisting of ten samples. The division was based on the specific decontamination and surface treatment techniques employed. The groups were subdivided based on the variables of colour stability, surface roughness, and shear bond strength for testing purposes.
The cleaning techniques employed in our investigation encompassed the use of hydrofluoric acid, phosphoric acid, an ultrasonic cleaning path containing distilled water, 70% alcohol, and hoover drying.
Prior to the bonding operation, all samples, with the exception of the control group, were exposed to artificial saliva solution to assess for potential saliva contamination. The application of artificial saliva was performed on the zirconia and vita enamic samples by means of a micro brush, at a temperature of 37°C, for a duration of 60 seconds. Subsequently, the samples underwent a rinsing process using a spray of distilled water for a duration of 15 seconds, followed by drying using an oil-free air dryer spray for a period of 30 seconds.
A shear bond strength test was conducted utilising a split Teflon mould with a diameter of 3 mm and a thickness of 5 mm. This mould was utilised to shape the BisCem resin cement and securely hold it in position on the surface of the specimens until it solidified. Each sample was mounted separately and horizontally onto a computer-controlled testing machine equipped with a 5 kN load cell. Data acquisition was performed using computer software. The occurrence of failure was indicated by the emission of an audible sound and the presence of visible signs of debonding between the resin cement and the surface of the ceramic sample.
The ceramic samples, which were exposed to surface treatment following contamination with spit, were analysed for colour characteristics using a spectrophotometer. The colour change (ΔE) is determined using the following formula: ΔE = [(ΔL)2 + (Δa)2 + (Δb)2].One-half.
The samples were affixed to the specimen holder, with the surface to be measured positioned horizontally. Subsequently, the specimen holder was vertically adjusted until the measuring tip made contact with the surface of the specimen. The task was successfully executed via a contact profilometer.
The findings from the shear bond strength and surface roughness analysis indicate that the hydrofluoric acid group exhibited the highest efficacy in removing saliva contamination from zirconia and vita enamic materials. This was followed by the phosphoric acid group, the ultra-sonic cleaning path with distilled water group, and the 70% alcohol cleaning techniques group. Conversely, the vacuum drying group demonstrated the lowest effectiveness as a decontamination technique for artificial saliva.
The findings of the colour stability study indicate that the ΔE values for all saliva cleaning procedures, whether applied to zirconia or vita enamic materials, were within clinically acceptable limits and had minimal impact on the materials’ colour stability.
findings: Based on the constraints of the investigation, the subsequent findings were derived:
1)The presence of saliva contamination led to a reduction in the adhesive strength between dental ceramics and resin cement.
2)The utilisation of hydrofluoric acid for clinical retreatment is favoured owing to its capacity to enhance the cementation process of dental ceramics. Hydrofluoric acid (HF) facilitates the attainment of a mechanical union by selectively exposing the crystalline structures present on the surface of the ceramic material. This process generates localised regions of micro retention, which contribute to the establishment of a strong bond.
3)Phosphoric acid has been found to be an effective technique for decontaminating ceramic surfaces from artificial saliva, since it has demonstrated successful removal of carbon-based pollutants.
4)The efficacy of ultrasonic route and alcohol procedures in removing spit contamination from dental ceramics is limited.
5)The influence of saliva contamination and various cleaning procedures on the shear bond strength and surface roughness of zirconia and Vita Enamic materials.
6)The colour stability of high transparent zirconia or Vita Enamic was not found to be impacted by artificial saliva or other cleaning procedures.